My MFD consistently shows about 6.5l/100km.
This should give me a range of about 850km/tank.
However, based on my calculations, it is more like 750km, or about 7.3l/100km.
I find that the last 1/4 of the tank produces much less that 1/4 of the total range.
Oddly enough my previous Golf 1.9TDI yielded much the same variances, although it was a little more economical.
There is a TB on the VWVortex site with an explanation on the fuel guage discrepancies but it doesn't explain my observations, nor bneeos's.